Urease is a key enzyme that leads to calcite precipitation and is produced in significant amounts in media containing urea and calcium sources (Stocks-Fischer et al., 1999; Muynck et al., 2010). All isolated strains produced amounts of urease. Among the isolates, the bacterial mixtures showed the highest levels of urease activity (29.2 mM), followed by KJ-47 (27.5 mM), KJ-46 (24.7 mM), B-21 (24.7 mM), and B-22 (21.7 mM) (Fig. 1).